The 12-year-old girl was surprised when she was ordered to the Voorhees Middle School office last week - and more surprised when she found out why.

Other students had accused her of "threatening to kill everyone," said her mother, South Korean-born Jennifer Um.

For hours, the sixth grader was questioned by school and police officials, then evaluated by a mental-health professional. The allegation was not substantiated and no disciplinary action was taken, the school said.

But the little girl was left "shocked and crying" and did not attend classes for two days, said her mother, who says the family now plans to move.

After the Virginia Tech massacre and the eighth anniversary of the Columbine High School bloodbath, edgy school officials across the country are not taking chances, but are wondering how far to go, say national school security experts.

"From the East Coast to the West Coast and from the Great Lakes to Florida, bomb and death threats have been reported over the past couple weeks - and I don't think school officials are overreacting," said Kenneth S. Trump, president and chief executive officer of National School Safety & Security Services, a school-safety consulting firm in Cleveland.

"Every year at this time, because of Columbine, we have a heightened security awareness and attention, but that was accelerated because of Virginia Tech, without a doubt."

Larance Johnson, program director of the School Violence Resource Center, part of the Criminal Justice Institute at the University of Arkansas, said inappropriate comments and threats from youths are "like an epidemic right now."

"Some kids think it's funny, a way of getting out of class, but authorities have to take it seriously," Johnson said.

In the Philadelphia region, the Delaware County Community College system was shut down for a week, until yesterday, after faculty members received e-mails "threatening to kill everyone." Purses and backpacks were banned, and metal detectors were installed.

In Gloucester County, a Williamstown High School student was ordered to leave school after creating an animation - on the day of the April 16 Virginia Tech massacre - showing one stick figure shooting another.

The 18-year-old was told he needed a psychiatrist's approval to return, but filed a federal lawsuit instead and was allowed back in school.

In Radnor, a high school student who allegedly tried to "shake down" another student for lunch money was arrested this week after he told police he had stashed a pistol in the high school, officials said. The school remained open and expected to open at the regular time today, with increased security.

And in Illinois, at Cary-Grove High School, an 18-year-old senior was arrested after he turned in a violence-laced essay last month and his principal called police. He was charged with two misdemeanor counts of disorderly conduct, and his personal computer was seized.

"You can't make an off-the-wall crack about explosives or terrorists in the airport, and that's the climate in schools since Columbine and Virginia Tech," said Trump. "Threats will be taken seriously. There is no such thing as a joke.

". . . Nine out of 10 threats are unfounded," he added, "but nobody wants to be number 10."

Johnson said the security concerns on school campuses now go beyond zero tolerance for weapons, to the content of verbal and written communications.

"You can find things in what they say and write," she said. "There are clues.

"If you are writing specific details on how to execute something, schools should take it seriously. . . . And if there is an allegation of a threat, school officials must at least ask questions and get to the bottom of it."

But accusations are not always supported by evidence.

In the Voorhees incident, five students allegedly approached the sixth-grade girl at her locker and - in an apparent reference to Virginia Tech - asked, "Are you going to kill us?" according an account provided by the Rev. Philip Lee, vice director of the New Vision Youth Community Center in Glenside.

Lee worked with the Um family after the trouble. The center provides counseling for Korean young people having problems with school, alcohol or drugs.

The Voorhees students told school officials that the 12-year-old girl had made a threat. She was summoned to the school office, where police later questioned her.

"Anybody can say bad words; nobody can believe it," said Jennifer Um, 49, who said she believes her daughter was accused because of her race. "At that age, they can be cruel."

She said school officials "treated my daughter like a terrorist. . . . Her only weapons were a pencil and eraser."

Because of the ordeal, Um said, she and her husband plan to sell their house and have enrolled their daughter in a private school in Moorestown.

Irene Afek, the Voorhees school's affirmative-action officer and spokeswoman, said officials did not target the sixth grader because of race and were following the school district's protocol when they investigated the allegations.

"We would do the same thing for any incident of this nature," she said. "Any threat is taken seriously, before or after Virginia Tech. This was not part of any backlash."

Lee said he had heard stories of other young Koreans having recent problems in school - including a Lansdale student who was suspended from school for a week for drawing a bomb.

Etzion Neuer, regional director of the Anti-Defamation League in New Jersey, said that the ADL had contacted Asian American groups, but that "we haven't heard of any widespread problems."

Neuer said schools must go beyond cameras, metal detectors and resource officers to "address the emotional welfare of the students as well, including issues of bias and bullying."

Contact staff writer Edward Colimore at 856-779-3833 or ecolimore@phillynews.com. To comment, or to ask a question, go to http://go.philly.com/askcolimore.